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Steven C Kazmierczak

Publications and source records attributed to Steven C Kazmierczak.

8 recordsLinked to original sources
PubMed2006

Electron spin resonance spectroscopy of serum albumin: a novel new test for cancer diagnosis and monitoring.

BACKGROUND: Proteins released by tumor cells can bind to serum albumin, leading to structural and functional modifications. We used electron spin resonance (ESR) spectroscopy to measure these changes in serum albumin and evaluate their utility for the diagnosis and monitoring of cancer. METHODS: We used an ESR spectrometer and 16-doxyl stearic acid as spin probe to measure conformational changes in albumin in blood samples from a population of healthy donors and volunteers (n=349), patients with a wide variety of hematologic and nonhematologic malignancy (n=135), and patients with chronic diseases such as gastrointestinal and pulmonary disease, diabetes, and cirrhosis (n=91). We added differing amounts of 16-doxyl stearic acid spin probe in ethanol to 50 microL of serum from each patient to create 3 different aliquots that differed in concentration of spin probe and ethanol, then incubated the aliquots for 10 min at 37 degrees C with continuous shaking. We measured the ESR spectra of each aliquot in triplicate and used proprietary software (MedInnovation GmbH) to evaluate the ESR spectrum for differences between cancer patients and the other groups. RESULTS: The diagnostic sensitivity and specificity of this test were 87.4% and 95.7%, respectively, for differentiating healthy individuals from cancer patients and 87.4%, and 85.7% for differentiating cancer patients from chronic disease patients. Serial evaluation of albumin conformation changes in several patients followed during the course of their disease showed excellent agreement between the magnitude of abnormality in the ESR spectrum of albumin and clinical and pathologic estimates of disease severity. CONCLUSIONS: ESR spectroscopy of serum albumin is a sensitive and noninvasive technique that clearly demonstrates diagnostic utility in patients with cancer. This test also enables monitoring of the disease course through use of serial measurements.

Adolescent↗
PubMed2006

Nanodiagnostics: a new frontier for clinical laboratory medicine.

BACKGROUND: The use of nanotechnologies for diagnostic applications shows great promise to meet the rigorous demands of the clinical laboratory for sensitivity and cost-effectiveness. New nanodiagnostic tools include quantum dots (QDs), gold nanoparticles, and cantilevers. QDs, which are the most promising nanostructures for diagnostic applications, are semiconductor nanocrystals characterized by high photostability, single-wavelength excitation, and size-tunable emission. QDs and magnetic nanoparticles can be used for barcoding of specific analytes. Gold and magnetic nanoparticles are key components of the bio-barcode assay, which has been proposed as a future alternative to the PCR. METHODS: We examined articles published over the past 10 years investigating the use of QDs, gold nanoparticles, cantilevers, and other nanotechnologies in promising diagnostic applications. RESULTS: Several nanodiagnostic assays have been developed, including a QD-based assay capable of detecting biotinylated prostate-specific antigen (PSA) at 0.38 ng/L, a bio-barcode assay capable of detecting 30 amol/L PSA in a 10-microL sample, and another able to detect 50 molecules of the Alzheimer marker amyloid beta-derived diffusible ligand in 10 microL of cerebrospinal fluid. CONCLUSIONS: Nanodiagnostics promise increased sensitivity, multiplexing capabilities, and reduced cost for many diagnostic applications as well as intracellular imaging. Further work is needed to fully optimize these diagnostic nanotechnologies for clinical laboratory setting and to address the potential health and environmental risks related to QDs.

Clinical Chemistry Tests↗
PubMed2005

False-positive troponin I measured with the Abbott AxSYM attributed to fibrin interference.

BACKGROUND: Serum is often used for the measurement of cardiac troponin I (cTnI). Previous reports suggest that fibrin present in serum samples collected for cTnI analysis may interfere with measurement of this marker. We investigated the incidence and magnitude of fibrin interference in serum specimens submitted for cTnI measurement using the AxSYM analyzer by performing duplicate analysis of all specimens with increased cTnI results. METHODS: Over a 4-month period, we analyzed 3692 specimens for cTnI with the Abbott AxSYM. Of these, 307 (8.3%) showed increased cTnI. A threshold of three times the precision of the method (15%) was used to judge discrepancies between duplicate analyses of specimens; all specimens being recentrifuged between the initial and repeat cTnI analyses. RESULTS: Of 307 patient specimens with elevated cTnI concentrations, 24 (7.8%) demonstrated differences of greater than 45% between duplicate analyses. Concentrations of cTnI obtained on initial analysis of these 24 specimens ranged from 2.4 to 24.0 microg/l. Repeat analysis showed the repeat values for 20 (83%) to be within the normal reference interval, with 16 (67%) showing concentrations of less than 0.3 microg/l. CONCLUSIONS: Our finding indicates that interference should be highly suspected in serum specimens where the initially measured cTnI concentrations is in the range of 2.0-25.0 microg/l when using the Abbott AxSYM. The finding of no interference in specimens with measured troponin concentration greater than 25.0 microg/l suggests that the interference effect of fibrin is generally not sufficient to cause spurious elevations of cTnI into this range. In addition, since switching to plasma as the specimen of choice for the AxSYM, we have not observed any discrepant cTnI results following duplicate analysis of over 200 patient samples with initial measured cTnI concentrations of 2.0 microg/l or greater.

Autoanalysis↗
PubMed2003

Laboratory quality control: using patient data to assess analytical performance.

Quality control plays a vital role helping to ensure the reliability of laboratory test results. The application of statistical quality control has been a component of laboratory medicine for approximately 50 years. Many of the control rules based on the early applications of statistical quality control have remained essentially unchanged since their initial introduction. Optimization of quality control rules can vary depending on the application for which a test is to be used. This review explores the various applications of laboratory quality control procedures and their role in identifying laboratory error. The ubiquitous use of computers in today's laboratories has enabled the development of more sophisticated means of assessing laboratory quality. The use of the Six Sigma technique and its adoption by the laboratory community is one example. Other examples include the use of patient-derived quality control procedures as a means of assessing laboratory performance. Early examples of these types of applications include use of Bull's algorithm, anion gap measurements, and delta checking. More recent applications include the correlation of laboratory test results, the average of normals procedure, and the Bhattacharya method.

Chemistry, Clinical↗
PubMed2002

Comparison of hemolysis in blood samples collected using an automatic incision device and a manual lance.

OBJECTIVE: To evaluate the magnitude of hemolysis in blood specimens collected from the heels of newborns using an automated blood collection device that uses a spring-loaded lance with blood collected using a manual lance. DESIGN: A randomized controlled trial involving 134 newborns assigned to have blood collected using either an automated blood collection device or a manual lance. A single experienced individual performed all blood collections. Serum hemoglobin concentrations were measured in all samples to gauge the extent of hemolysis. SETTING: A neonatology unit in a 740-bed tertiary care teaching hospital. PATIENTS: Healthy newborns with gestational ages ranging from 33 weeks to 41 weeks. Blood samples were collected from study participants at between 7 and 126 hours postpartum. Group 1 consisted of 66 individuals who had blood collected using the manual lance. Group 2 contained 68 individuals with blood collected using a spring-loaded automatic lance. MAIN OUTCOME MEASURE: Plasma hemoglobin content as an indicator of the extent of hemolysis. RESULTS: There were no significant differences between newborns in groups 1 and 2 with respect to gestational age, birth weight, or time interval between birth and time of blood collection. We found a highly significant difference with respect to plasma hemoglobin concentrations in specimens collected with an automated lance (hemoglobin, 2.35 g/L) vs that collected using the hand-held lance (hemoglobin, 4.85 g/L). CONCLUSION: Use of an automated spring-loaded lance allows for the collection of blood specimens with smaller levels of plasma hemoglobin.

Birth Weight↗